Gas analyzing process and apparatus



.Feb. 13, 1934- J. D. MORGAN 1,947,303

GAS ANALYZING PROCESS AND APPARATUS Filed March 14. 1932 8 Elk-w 74 i:,l. H W v 0 x H 7 JOHN D.MOR6AN Patented Feb. '13, 1934" 1,947,303 GASANALYZING PROCESS AND APPARATUS John D. Morgan, South Orange, N. 1.,asslgnor to Dohe'rty Research Company, New York, N. Y., a corporation ofDelaware Applieatlon March 14, 1932 Serial No. 598,607

15 Claims. 236-15) This invention relates to combustion control and moreespecially it relates to a method and apparatus for rapidly andaccurately controlling the supply to a combustion zone of one or moreelements of combustion. It has special utility in the control ofcombustion in an internal combustion engine of the automotive type,although it is adapted'for use in the various types of heating,andheat-treating furnaces when op-' erated' either over-ventilated orunder-ventilated. It has long been known that a diffusion cell made upof two chambers separated by a porous gas pervious wall can be used forindicating the presence in the air of mines of a small amount of certaingases such as flre damp or gas damp.

When thus used, one of the chambers, after being filled with air, isplaced in the mine at. the point where the air is to be tested. It isnow known that the rateof diffusion of a gas through 2 a porousdiaphragm at a given temperature and pressure is inversely proportionalto the square root of the density of such gas. Therefore the lightergases in the mixture will penetrate through the porous wall in onedirection more readily than the heavier gases flow in the oppositedirection through the wall, resulting in an increase in pressure in onechambenwhich may be measured directly or may be employed for giving asuitable warning signal. The diffusion 520 in apparatus of this typeheretofore known has been slow and the rate of pressure increase thereinhas been low, making it unsatisfactory for the.

. determination of combustion eificiencies where quick determinationsare. necessary in order to permit prompt adjustment of the-air and fuelflowing to the combustion zone. Furthermore it required manualoperation, and great care "was needed if comparable results weredesired, since the time of exposure of the fluid to the dia- 40 phragmis an important element.

The'gases normally formed in combustion operationscontain varyingmixtures .of carbon monoxide, carbon dioxide, hydrogen, methane,nitrogen, oxygen, and sometimes other lwdrocar bone in small amounts.For instance, in the exhaust gases flowing from an internal combustionengine of the automotive type, the percentages ."of the above gasestherein vary about as follows:

Carbon dioxide 5.7% to 13.4% C0 13% to 1.2% Oxygen; -l 1.1% 1.1%Hydrogen 7% to 1.2% Nitrogen 71.5% to 84% CH4 1.7% to .1%

The first and second values given for each gas are those found in theexhaust gases from operations at 50% and 95% combustion eflici'encyrespectively. The relative rates ofdifiusion of these gaseous componentsthrough a phragm are as follows:

Hydrog I i 1 porous dia- Carbon dioxide Carbon monoxide .267 Nitrog n.267 CH4--- .354 Oxyg n .250

Prior to thepresent invention, therefore, a determination of the amountof reducing gases in air required considerable time with the result thatsuch methods were-not adaptedfor the continuous control of an element ofcombustion flowing to a combustion operation. Applicant has nowsucceeded in devising a method and an apparatus operating upon thediffusion principle for obtaining rapid indications of the amount ofreducing gases present in a combustion gas mixturecontaining a number ofdifferent reducing gases, and he has likewise adapted apparatus of thistype for continuously controlling the efliciency of a combustionoperation.

' According to the present invention a sample of the gases from acombustion operation is continuously withdrawn from a motorexhaust or afurnace and, after being suitably filtered and cooled to a uniformpreselected temperature,-- and preferably stripped of any condensedmoisture,-is passedinto a compartment of a diffusion cell that isseparated from another compartment of the cell by a porous diaphragmsuitable composition such' as a mixture of asbestos and steatite moldedand flred to the point of vitrification. The diaphragm and associatedparts are so designed that 'there is relatively a very large diaphragmsurface through which the diffusion may occur; while at the same timethe space 'into which the reducing gases diffuse through the diaphragmis. very small, so that a very rapid diffusion of gases mm; small spaceis facilitated. In this manner, a rapid increase of pressure isdeveloped within the interior space upon passing gases containing lightreducing constituents along the opposite face of the dia-' phragm. Thispressure then acts upon a suit-.

able manometer or equivalent device by'which it is possible, aftersuitable calibration, to measure the change in pressure developed withinthe second or inner chamber in terms of the percentage of reducing gasesor combustible constituents in the combustion gases being examined. J

A scale may be associated with' or mounted on the manometer to indicatethe amount of reducing gases in the-combustion gases in terms ofcombustion efliciency of the operation pro-- ducing them. When gasolineor like liquid fuel is combusted in an internal combustion engine of theautomotive type the scale may be made in accordance with the followingtable:

Percent of Percent reducing ggggg:

gases money By suitable arrangements of parts, hereinafter described,the diifusion apparatus is operated intermittently at regular intervalsof time and may be adjusted for varying the time interval as desired.Similarly provisions are made for automatically and periodicallyadjusting the flow of fuel and/or air to the combustion operation atfrequent intervals, in accordance with the pressure existing within thediffusion apparatus at regular intervals synchronized with respect tothe flow of combustion gases to the diffusion cell.

Such fuel or air adjustments are then maintained until the nextadjustment is effected at the end of the succeeding diffusion period.Between each diffusion measurement the inner pressure-building chamberis purged with air or other gas selected as the standard.

By the proper design of difiusion cell so as to obtain as nearly aspracticable a maximum of diaphragm surface and a minimum of space in theinner pressure compartment, these successive determinations may becompleted and furnace condition adjustments made in periods as short as30 seconds or one minute.

In the accompanying drawing illustrating more or less diagrammaticallyapparatus adapted for the practice of the process, Fig. 1 is a somewhatdiagrammatic showing of one form of such an apparatus assembly, partsbeing broken away;

Fig. 2 is a horizontal section through the diffusion cell of Fig. 1taken along the lines'2--2 thereof;

Fig. 3 is a somewhat diagrammatic showing of one form of apparatus forfuel and air control;

Fig. 4 shows in vertical section another form .of diffusion cell andinterassociated parts, portions being broken away;

Fig. 5 is a view taken along the line 5-5 of Fig. 4; and

Fig. 6 is a horizontal section taken along the line 6-6-of Fig. 4.

Referring now to Fig. 1, numeral 10 designates a furnace provided with afluid fuel inlet 12 and an air inlet 14, the latter being connectedthrough suitable piping with the fan 16 driven by a variable speed motor18.

For removing from the combustion zone a sample of gas to be examined andfor preparing it for the difiusion operation, there is provided acombustion gas ofitake 20 leading from the furnace to a dry filter anddrip trap 22, the latter of which may be filled with suitable filteringsubstance such as glass, steel wool or cotton. From vessel 22 a conduit24 conducts the filtered gases through water-cooled condenser 26 andthence to a rotaryvalve 28, operated by a motor or the like (not shown)through suitable gearing adjusted to effect a complete rotation-of aninner member 30 of the valve ina preselected time, which maybe adjustedin accordance with the nature of the gases being examined but willgenerally range from one to one and one-half minutes and upward.

For the purpose of effecting the separation and isolation of differentcomponents of the gas mixture in accordance with their specificgravities, there is provided a cell or chamber 32 connected with thevalve 28 through the conduits 34 and 36. A conduit. 38 connects thevalve 28,with an aspirator 40, adapted to function under the effect ofwater discharged through the nozzle 42 direct from a source of supplyunder pressure through line 44,-or the water employed in condenser 26may be utilized. The aspirator is provided with the usual outlet 46.

Valve 28 has provided therein a pair of passageways so constructed thatthe respective pairs of lines 24 and 34, and the lines 36 and 38successively may be interconnected therethrough.

Mounted within the cell or chamber 32 is an annular porous diaphragm 48separating the space within the cell into a pair of chambers includingan outer chamber 50. The diaphragm is of such shape as to have as largeas practicable an area of exposure to the gases flowing through chamber50. In the form shown this diaphragm is star-shaped, A filler member 54,preferably hollow, is provided within the porous member 48, with itsside walls spaced close to the inner walls of the latter, defining withthese walls a narrow irregularly shaped inner chamber 56. The diaphragm48 and member 54 may be corrugated to increase the surface fordiffusion. The member 54 is made of gas-impermeable material such asmetal or its equivalent.

The diaphragm 48 and member 54 are mounted on a base 58 in such manneras to prevent flow of gases between chambers 50 and 56, exceptingthrough the diaphragm. A flat top portion or member 60 serves a similarpurpose.

The chamber 56 is in communication at its top with a central tubularmember 62 which extends upwardly through the filler member 54. Thistubular member 62 extends tln'ough the base 58 of the cell and is thencurved to form a leg of 12 manometer tube 64 of small diameter as shown.

The lower part of the chamber 56 is provided with valved outlet lines 66for the periodic release of any pressure developed therein and for thepurging of the chamber. Preferably the outlet 125 lines 66 are providedwith valves operating in synchronism with the valve 28 whereby at thatpoint in the path of travel of the inner valve member 30 immediatelyfollowing the point reached when the combustion control devicehereinafter described is actuated, the pressure in chamber 56 isreleased through the lines 66.

For this purposethe lines 66 lead to an automatic valve or valves 6'7leading to waste, the said valves being operated in synchronism with thevalves 30' through cams 73. A conduit connected with a source of air orother gas under pressure is connected with the upper part of the chamber56 through a conduit 69 controlled by a valve 71 operated in synchronismwith the valve 30 through cam 75.

The leg of the manometer 64 outside of the cell 32 is open-ended and isprovided with a plurality of vertically-spaced pairs 'of electriccontact members, here respectively designated 68, 70, '72, 74 and '76.Within the manometer is a body of a non-conducting liquid such as lighthydrocarbon oil or other suitable organic fiuid, above the surface ofwhich a member '78 is adapted to float. This float member is providedwith suitable coni v 1,947,303 ducting material such as platinum foilfor the respective solenoid-operated. valves 84 and- 86 having openingsof different sizes, each of the valves 84 and 86 being under the controlof respective pairs of solenoids 88 and 90, in an electric circuit whichcomprises a battery or other source of constant electric potential 92and the various pairs of contacts 70, '72, 74 and 76. The arrangement issuch that the solenoids 88, when actuated, act to move the valvesassociated therewith in the opposite direction to that in which they aremoved by the solenoids 90 when the latter are actuated.

The lowermost pair of contacts 68 is in circuit with a solenoid 98adapted to adjust the flow of current through the three-phase circuitfor operating variable speed motor 18. The arrangement is such that uponthe completion of the circuit through the pair of contacts 68, thesolenoid 98 is actuated in well-known manner to increase the speed ofthe motor 18 above the normal rate and thus supply more air to thefurnace.

For synchronizing the operation of the diffusion apparatus with thedevice controlling the flow of fuel and air to the furnace so as to makethe latter responsive to conditions in the former at the momentimmediately prior to the time at which the pressure built up in theinner pressure chamber 56 by diffusion thereto is released,-

the valve 28 is provided with a pair of electric contact members 100adapted to be periodically,

interconnected through a conductor 102 mounted in the rotary member 30of the valve. These elements 100 form part of an electric circuitcomprising wires 104, 106 and the source of 'elec-- tric current 92. Thearrangement is such that just prior to the moment at which'the pressurethat has been built up in the chamber 56 is released through lines 66,the electric circuit containing the various solenoids is momentarily.closed and one of the solenoids is energized to adjust the fuel or airflow to the furnace.

Fig. 3 illustrates another formof mechanism adapted for energizing thevarious solenoids shown in Fig. 1. According to this modification, thefree end of the manometer tube 64 isassociated with a-pressure=operatedregulating apparatus 110 of well-known construction, having mountedtherein a flexible diaphragm 112 of suitable material. The diaphragm 112is operatively connected with a reciprocating member 114 through thelever member 116 and link 118. The

lever 116 is fulcrumed as 'at 120 and is counterbalanced so that aminimum of pressure is required beneath the diaphragm for actuating themember 114. The last-named member is movable in, guides 122 and hassecured to it at spaced points slotted socket members 124, each adaptedto house one end of respective levers 126, the

other end of each lever being connected with one of a pair of pivotedmercoid liquid-operated switches 128. The construction of this apparatusis such that when atmospheric pressure exists in the legs of themanometer 64, the respective switches 128 are horizontallydisposed butthat I indicated;

as the pressure in the manometer varies from In Figs. 4 to 6 isillustrated a form of diffusion cell in which the inner orpressure-developing r chamber 56 is divided into a plurality of separatecells by the partition members 130. These members as shown extend fromthe outer wall of the cell 32 to the wall of tube 62; or they may extendfrom the outer cell wall to the casing 54. The chamber 56 is therebydivided into a number of spaces of equal volume 156, each being adaptedto be separately and successively connected with the manometer tube 64.The construction is such as to prevent the escape of pressure developedin one space 156 into any of the other spaces.

l'n this modification, the tube 62 is in the form of a hollow sleevevalve 162 rotatable in an outer fixed valve tube 164/ the latter ofwhich is in communication at its lower ends with the manometer 64. Aslot 166 in the upper end of valve 162 is adapted to successivelyregister'with' each of a number of slots in the tube 164, each leadingto one of the respective spaces 156 for connecting each of the latter inturn with the manometer. A shaft 167 at the lower end of the rotarymember 162 has mounted thereon cams 168 and 1'10, adapted successivelyto contact with yielding valves on the respective outlet lines .66,andon I the combustion gas inlet lines to the chambers 50. A cam 174 onan extension of member '162 coacts successively with yielding valves onair lines leading from a leader 175 to each inner space 156 opposite theoutlet lines66. Gas inlets 15'? and gas outlets "159 to the respectiveouter chambers 50 are so connected respectively with the conduits 34 and36 that while the gas mixture being tested is being passed through oneof the compartments 50, it is cut off from the others. Alternatively anumber of single diffusion cell units may be operatively interconnectedin any other suitable manner to function in the manner By so designingthe diffusion cell as to provide an inner pressurechamber of smallvolume and one which is under the pressure effect of gas diifusingthrough a porous diaphragm of very rextensive diffusion surface, thistype of diffusion device has been successfully adapted for the controlof a combustion operation where a quick response to changes inconditions within the combustion zone is necessitated. It is possible tobuild up sumcient pressure rapidly so as to make successivedeterminations at spaced intervals offrom 30 seconds to 1% minutes ormore.

the valve 28. Thus any foreign matter and moisture is removed from thegases. The inner member ofthe valve is continuously rotated under theaction of a constant speed motor or the like whereby intermittently fordefinite periods of time, the gases flow into and through the outerchamber of the difiusion cell and thence out through conduit 36, valve28 and .conduit 38 to,

a point of discharge. During this period of operation the lightergravity reducing constituents such as hydrogen and carbon monoxidepresent in the gases tend to diffuse through the porous diaphragm to thesmall inner chamber 56 more rapidly than the components of the air inthe latter diffuse outwardly therefrom. There thus results a rapidincrease of pressure in the inner vesse and in the small or capillarymanometer tube 64 connected therewith. The floating electric contact 78rides upon the top of the liquid in the manometer tube and as it reachesthe level of each pair of contacts it is adapted, when contacts 100, 100are interconnected, to close the electric circuit and energize acorresponding solenoid. As the inner member 30 of the valvecontrollingthe flow of gases to the diffusion cell continues to rotate, the flow ofgas to the diifusion cell 32 is cut ofi for a predeterminedperiod. Justprior.

to the resumption of gaseousflow through line 24 to the cell 32, thepressure developed in the inner chamber 56 is released by a yieldingvalve in line 66 which is periodically operated by a cam mounted on ashaft 180 interconnected by gearing (not shown) withthe mechanismrotating the inner valve member 30.

The arrangement of parts controlling the operation of rotary member 30andthe valves in conduits 66 is such that just prior to the release ofpressure'in the inner chamber '56 the main electric circuit is closedthrough the connector 102 in the rotating member 30. Thereupon a currentflows through that pair of contactor members temporarily connected atthe momentby the floating contactor 78. The solenoid in such circuit isthen energized, either to open or to close a. needle valve controllingthe flow of fuel to-the furnace, or to modify the volume'of air fiowin'gto the furnace'from fan 16. 'A moment later the circuit is again brokenat the rotarymember 30, and the valves 67 are closed. Thesolenoid-operated valves are-so constructed that they hold theiradjustment when the solenoids operating them are de-energized.

The fluid in the manometer tube may bean electric conductor such asmercury instead of the non-conductor described above. In such instancethe contacts in the manometer tube' are so disposed that the currentflowing in this case through the mercury of the manometer, when the mainelectric circuitmomentarily is closed, successively. energizes thesolenoids to open or close one fuel valve afterthe other as needed.The'electric contacts 68 are located in the other leg of the manometertube in this modification. One lead wire connects with the mercury atthe lowermost point in the manometen Various other means than thoseshown may be employed for causing electric current to flow through thecircuit at predetermined regular intervals, for the purpose stated.

In instances where the control of combustion Within an internalcombustion motor is desired, the construction of the burner 14, fan 16and associated parts may be modified in suitable manner to provide for.carburetion,-the usual air inlet and Venturi orifice being provided inline 12 between the valve 84 and the motor. The motor 18 under thecontrol of the solenoid 98 may then be employed for operating abutterfly valve in the air inlet line.

While air is the gas generally employed as the standard gas within theinner chamber 56 when beginning the difiusion operation upon a gas beingexamined, it is within the scope of the present invention to employ inplace thereof, hydrogen, helium or other gases having a low specificgravity and a high rate, of difiusibility,- or a high gravity gas suchas carbon dioxide.

The invention is susceptible of modification within the seope'of theappended claims.

I claim:

1. In a porous diaphragm gas analyzer contaming an analyzer cell,automatic intermittently within the said cell, means for intermittentlyreturning the pressure within the cell to a preselected standard, andautomatic meansresponsive to the pressure within the cell at successivepreselected periods and adapted to adjust the fiow of an element ofcombustion to a combustion chamber.

3. Apparatus for controlling a combustion operation which comprisesmeans, including a porous diaphragm, responsive to the reducing"constituents in a gas mixture and tending to maintain the reducingconstituents ,in such mixture at a constant minimum value, andperiodically-functioning means responsive when so functioning to adeparture of the said reducing constituents from the said minimum valuefor progressively adjusting the first-named means to restore thereducing constituents to the said minimum value.

4. Automatic means for controlling the flow of an element of combustionto a combustion chamber, which comprises in combination a cell, a porousdiaphragm within the cell and adapted to divide the interior thereofinto two gas chambers, means for flowing a fluid mixture through one ofsaid chambers, pressure-responsive means op eratively associated withthe other of said chambers, means for controlledly connecting the lastnamed chamber with the atmosphere for displacing the gas in suchchamber, a conduit leading to a combustion zone and adapted to conductthereto an element of combustion, and means controlled by the saidpressure-responsive means adapted to regulate the flow of thesaidelement of combustion through the conduit.

for flowing a fluid mixture through one of said chambers, pressureresponsive means operative- 1y associated with the other ofsaid-chambers, means for controlledly connecting the last named chamberwith a source of fluid of known composition, a conduit leading to acombustion zone and adapted to introduce thereto a'fluid element ofcombustion, and means including an electric circuit controlled by thesaid pressure responsive means for regulating the flow of the saidelement of combustion through the said conduit.

-6. Automatic means for controlling the efficiency of a combustionoperation which comprises in combination a cell, a porous diaphragmasso-" 'ciated with the cell and adapted to divide the interior thereofinto two gas chambers, means for withdrawing exhaust gases from acombustion chamber and for filtering the same and cooling them to-apreselected'temperature, means for introducing the filtered and'cooledgases into one oi the said gas chambers, pressure responsive meansoperatively associated with the other of said gas chambers, a conduit.connected with the combustion chamber and adapted to conduct an elementof combustion thereto, and means controlled by the said pressureresponsive means for regulating the how of the element'of combustionthrough the conduit, the said diaphragm and cell being of such shapeandsize as to provide in the cell a very large diaphragm diflusionsurface and a very small gas space in the last-named gas chamber.

7. Automatic means for controlling the flow of an element of combustionto a combustion ohame ber which comprises in combination a cell, a gasimpermeable member withi'n the cell, 'aporous diaphragm within thecell-and surrounding and closely adjacent to'the last-named member anddefining therebetween an inner gas'chamber on small volume, and definingwith the cell walls an outer chamber, and means for flowing a fluidmixture to be tested through the said outer cham* ber in contact withthe said diaphragm, pressure responsive fneans operatively associatedwith the said inner chamber. of small volume, means forcontrolledlyconnecting the last-named chamber with asource'oi fluid ofknown composition for displacing the gases present in the said chamber,a conduit leading to a combustion chamber and adapted to *convey theretoat least one fluid element of combustion, and means controlled by thesaid pressure responsive means for rjgulating the.

flow of fluid through the said cond 8. Automatic mechanism forcontrolling the efilciency of a combustion operation which comprisesmeans for withdrawing exhaust gases from such combustion operation,means for cleaning and cooling such gases, and for removing condensedmoisture therefrom, means for passing the cleaned and cooled gases undercontrolled conditions of pressure into contact with a gas pernieablediaphragm separating two gas zones, pressure responsivemeans'operatively associated with one of the said gas zones, meansincluding an electric circuit controlled by the said pressure responsivemeans for regulating the flow of combustion supporting gas. to /thecombustion zone, means for periodically discontinuing the flow ofexhaust gases in contact with the said diaphragm and for releasingthe'pressure on the gas zone'associated' with the pressure responsivemeans, and means for closing thefsaid electric circuit for a shortperiod immediately prior to the said release of pressure. i

9.- Mechanism for regulating the flow of an ele-' tric switch, saidswitch being in a normally open electric circuitv adapted respectivelyto control the flow of air and fuel to the combustion chamber, means forperiodically discontinuing the flow of gas through the outer chamber,and means associated with the last named means for peri odically closingthe said electric circuit.

10. The method of controlling a combustion operation which comprisescleaning and cooling exhaust gases from a combustion operation,

bringing the gases into contact for a preselected period of time with aporous diaphragm surrounding a gas-tight space,and utilizing thepressure condition in the said space at the end of the said period oftime for adjusting the flow of an element of combustion to the saidcombustion operation.

11. A gas analyzing method, comprising withdrawing'waste gases from acombustion opera-' tion, filtering" the same and cooling them to auniform" regulated temperature, dii fusing the .flltered and cooledgases through a porous diaphragm into a small enclosed space containinga control gas, intermittently measuring the re-' sultant gas pressurewithin the saidenclosed space, and subsequently releasing the pressurewithin the enclosed space and purging the difiused gases from the latterwith thesald control gas.

12. A gas analyzing method, comprising with-- drawing waste gases from acombustion operation, filtering the same and diffusing the filteredgases through aporous diaphragm into a small enclosed space containing acontrol gas, intermittently measuring the resultant gas pressure)ivithin the saidenclosed space, and thereafter purging the difiusedgases from the latter.

13. In a porous diaphragm gas analyzer, in combination ,a cell, a porousdiaphragm within the cell and adapted to divide the interior thereofinto two gas-tight chambers, means for flowing a fluid-mixture at a,regulated rate through one or the said chambers, calibratedpressureresponsive means operatively connected with the other of'thesaid chambers, automatic means for controlledly connecting thelast-named chamber with the atmosphereat spaced intervals ,and fordisplacing the gas in that chamber, and automatic means adaptedperiodically to flllthe lastnamed chamber with a standard gas.

1 4.In a'porous diaphragm gas analyzer, a gas tight analyzer celldivided into a large compartment and'a small compartment by a porousdiaphragm having a large surface area, means adapted to conduct filteredcombustion gases through thes'aid large compartment, meansforinterrupting the said gas flow at regulated intervals, means responsiveto the pressure in the other of said compartments, means controlled byvthe said pressure-responsive means and adapted when energized to adjustthe flow of an elementbi combustion to a combustionchamenergizing thelast-named means.

15. In a porous diaphragm gas analyzer, an analyzer cell divided into alarge compartment and a small compartment by a porous diaphragm ber, andautomatic mechanismior periodica1lyof combustion to a combustionchamber, automatic mechanism for periodically energizing the last-namedmeans, and means associated with the small compartment for periodicallypurging the latter of combustion gas components by means of a standardgas.

JOHN D. MORGAN.

